von Willebrand Disease in Chronic Immune Thrombocytopenic Purpura Children.

Purpose: von Willebrand disease (vWD) is the most common hereditary bleeding disorder and type 2B combines thrombocytopenia. So it must be considered in patients found to have low platelet counts, particularly if there is a family history of mucocutaneous hemorrhage. We performed this study to diagnose the type 2B vWD in chronic immune thrombocytopenic purpura (ITP) children.

Methods: Seventeen cases among chronic ITP children over 6 months at the Department of Pediatrics, Kyungpook National University Hospital, Daegu, Korea from October, 1995 to June, 2007 were participated in this study. We performed screening coagulation tests such as platelet counts, activated partial thromboplastin time (aPTT), and bleeding time (BT) and specific tests for vWD such as von Willebrand factor related antigen (vWF: Ag), vWF ristocetin cofactor (vWF: RCo), factor VIII, and vWF multimer on these patients. These tests were also performed their family when the patient was diagnosed vWD. And we reviewed their past and family histories about bleeding tendency.

Results: There were four boys and thirteen girls and their mean age was 11.6 years (range: 2.8∼18.5 years). Five cases (5/17, 29.4%) were diagnosed vWD: one had lower level of vWF: RCo and factor VIII with normal level of vWF: Ag and others had lower level of vWF: RCo and vWF: Ag with normal level of factor VIII. Among these, two cases showed abnormal screening test results, prolongation of aPTT or BT. We could perform the vWF multimer test in two cases, but two had normal pattern. Among five vWD children, we could obtain the past and family bleeding tendency histories except one case and three families showed bleeding tendency. But all families showed normal screening and specific test results.

Conclusions: von Willebrand disease was combined in 5 cases (29.4%) among 17 chronic thrombocytopenic children. More evaluation such as vWF multimer and ristocetin induced platelet aggregation test (RIPA) is needed to confirm the subtype. And we should repeat the evaluation to the family who had bleeding history but showed normal results for diagnosis or exclusion of vWD.